The transitional epithelium lining urinary bladder is susceptible to chemical carcinogenesis. The morphological development of cancer in this tissue has been characterized in rat models. Due to the small amounts of tissue available it has been difficult to conduct physiological studies. A method for the in vitro growth and differentiation of normal epithelium from rats has been developed, allowed studies concerning cyclic AMP metabolism and hormonal regulation to begin. Results obtained with normal epithelium are being compared to data obtained with transformed lines derived from transitional epithelial tumors of Fischer rats fed N-(4-(5-nitro-2 furyl)-2-thiayolyl) formamide. These studies are being carried out in order to test the hypothesis that the alterations in structure, growth and function of transformed transitional epithelium may be related to changes in the metabolism of cyclic AMP and consequently its relationship to hormonal regulation. This hypothesis is being tested by examining the effects of hormones on cyclic AMP metabolism in cultures of normal transitional epithelium and the transformed epithelial cells. The hormonal sensitivities and kinetic properties of the enzymes of cyclic AMP metabolism (adenylate cyclase, cyclic nucleotide phosphodiesterase, and protein kinase) will be compared in normal and transformed cells in an effort to uncover lesions associated with the neoplastic state. Chronic experimental manipulation of cyclic AMP levels with agonists of adenylate cyclase and antagonists of phosphodiesterase will be performed to ascertain the effects of cyclic AMP upon the growth, morphology and regulatory mechanism of normal and transformed cells. This project will contribute to an appreciation of the physiological and biochemical changes that occur with neoplasia of the transitional epithelium, and may prove valuable to future developments in the area of pharmacological therapy of bladder cancer.